We have a remarkable ability to learn and recognize the behavioral significance, or category membership, of objects and events in our environment. Diseases that disrupt this ability, such as Stroke, Alzheimer's disease, and Schizophrenia, can cause serious problems in the daily function of affected patients. While the ability to categorize stimuli and events is critical to our ability to interact with the world, little is known about how these categories are learned. Furthermore, much remains to be understood about how categories and other abstract phenomena are stored in memory. A mechanistic understanding of how we learn the behavioral relevance of stimuli and how such information is loaded into memory could greatly enhance our ability to treat diseases that affect cognitive function. Prior work has revealed that neuronal activity in two interconnected cortical areas, the lateral intraparietal (LIP) area and lateral prefrontal cortex (LPFC), show strong and robust encoding of the category membership of stimuli following long-term training. However, relatively little is known about how neuronal category representations develop during the learning process itself, and how category- representations stored in long-term memory are transferred to short-term memory during behavior. The goals of this project are to elucidate the behavioral and neuronal dynamics of category learning in LIP and LPFC, and to understand how task complexity affects representation of information in short-term memory. First, we will record from populations of LIP and LPFC neurons during the category-learning process in order to understand how neuronal category representations develop as a function of learning. Second, we will examine the task-dependence of mnemonic neuronal representations in LIP and LPFC by comparing neuronal activity in subjects during visual categorization and identification tasks with the same set of motion stimuli. The results of these studies will yield a mechanistic understanding of how the brain learns abstract information about visual stimuli and maintains it in memory. The long term goal of the proposed studies is to provide a basis for the understanding and future treatments of the diseases and conditions which affect learning, memory, and recognition. In addition to neurological disorders such as Stroke and Alzheimer's disease, work on conditions that affect learning such as Attention Deficit Disorder and Dyslexia could benefit from a more detailed understanding of the brain mechanisms underlying learning and memory. Thus, the knowledge gained from studying the neural basis of learning and memory will likely shed light onto valuable next-generation treatments for neurological and cognitive disorders.